Writing and reading CoE objects using function blocks

The function blocks "FB_EcCoeSdoReadEx" and "FB_EcCoeSdoWriteEx" from the Tc2_EtherCAT library can be used to read and write CoE values in the PLC project.

To use the function blocks, proceed as follows:

1. Add the "Tc2_EtherCAT" library:

Writing and reading CoE objects using function blocks 2:

2. Right-click on "References" in the PLC project and select "Add library". The "Add Library" dialog box opens.

3. Select "IO" -> "Tc2_EtherCAT" and close the dialog box with "OK".

4. The Tc2_EtherCAT library is now displayed under References in the TwinCAT tree.

5. Press the "F2" button to open the input wizard.

Writing and reading CoE objects using function blocks 3:

6. Activate the checkbox "Insert with arguments" and select the function block

"FB_EcCoeSdoReadEx" for reading CoE values or

"FB_EcCoeSdoWriteEx" for writing CoE values

7. Confirm with "OK". The "Auto Declare" dialog box opens.

8. Instantiate the function block in the "Auto Declare" dialog box by entering the name and confirming with "OK".

9. Initialize the function blocks in your PLC program. Use the following sample code for reading and writing the "DC OK threshold" (0x8000:16) as a guide.

Writing and reading CoE objects using function blocks 4:

Code sample: Reading and writing the CoE value for the DC OK threshold

10. After starting the controller and logging in, you will see the following screen:

Read command:
A positive edge of "startRead" starts the read command. The value of the variable "fDCOKthreshold" is written.

Writing and reading CoE objects using function blocks 5:

Online data for reading and writing the DC OK threshold

Write command:
A positive edge of "startWrite" starts the write command. The CoE object 0x8000:16 "DC OK threshold" is read and the value in the variable "fDCOKthreshold" is written to the CoE object "DC OK threshold" 0x8000:16.